System for tissue dissection and retraction

ABSTRACT

A system for tissue dissection and retraction is disclosed herein. A tissue dissection assembly generally comprises an elongate body shaft, an actuation member movable relative to the elongate body shaft, and at least one dissector arm member having at least a first end attached to the elongate body shaft, wherein the at least one dissector arm member is adapted to reconfigure within a plane from a low profile to an expanded profile when urged via the actuation member, and wherein the at least one dissector arm is further adapted to dissect tissue within the plane. In use, the assembly dissects tissue within the plane typically by advancing the elongate body shaft into the tissue region where the dissector arm member or members are then reconfigured within the plane from its low profile to its expanded profile to thereby dissect the tissue region along the plane.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/174,253 filed Jul. 1, 2005, the contents of which is incorporatedherein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to systems for dissecting and/orretracting tissue. More particularly, the present invention relates toapparatus and methods for dissecting layers of tissue as well asretracting tissue regions and organs.

BACKGROUND OF THE INVENTION

Conventional instruments and methods for obtaining access to regionswithin the body by dissecting tissue and retracting tissue and organshave been previously accomplished through various mechanical methods.Previous devices have included expandable tissue dissectors andretractors used for dissecting or moving sub-surface tissue inarthroscopic and endoscopic surgery percutaneously introduced into apatient through small incisions made in the skin.

Many of these devices are configured to simply expand from a low profileinto an expanded profile to simply provide a surface, whether by anexpanded structure or via a sheath or covering, for retracting tissueregions within the body. Other devices are also expandable into anexpanded profile to not only provide a retraction surface but also todissect sub-surface regions of tissue. In either case, these devices aretypically configured to mechanically expand in a number of differentplanes while other devices are configured to expand within a singleplane. Most of these tools are mechanically expandable in a number ofdifferent configurations, for example, expandable mechanical trusses,pivoting interleaved configurations, projecting loops, etc.

Still other devices have utilized expandable balloons which are inflatedwithin the patient through various methods. Generally, expansion isaccomplished by inflating the balloon with a fluid or a gas, e.g.,carbon dioxide, water, saline, etc., until the balloon is sufficientlyexpanded. Such balloons have also been utilized for retraction of organsand tissue regions once expanded. However, such balloons are typicallylacking because they generally lack sufficient rigidity and cannot becontrolled to conform to various sizes or shapes for preciseapplication. Moreover, adequate retraction of tissue can only beaccomplished when the balloon is fully expanded.

Accordingly, there is a need for instruments which are sufficientlyminimally invasive for passage into a patient and which are alsosufficiently rigid and precisely controllable.

BRIEF SUMMARY OF THE INVENTION

An instrument which enables a surgeon to obtain access within apatient's body through controlled dissection between tissue layers maybe advanced percutaneously through one or more incisions made in apatient's skin or through an open surgical procedure.

Such a tissue dissection assembly may generally comprise an elongatebody shaft, an actuation member movable relative to the elongate bodyshaft, and at least one dissector arm member having at least a first endattached to the elongate body shaft, wherein the at least one dissectorarm member is adapted to reconfigure within a plane from a low profileto an expanded profile when urged via the actuation member, and whereinthe at least one dissector arm is further adapted to dissect tissuewithin the plane.

In use, such a tissue dissection assembly for dissecting tissue within aplane or along a line may be utilized generally by advancing theelongate body shaft into a tissue region to be dissected, urging the atleast one dissector arm member positioned adjacent to or within thetissue region to reconfigure within a plane from a low profile to anexpanded profile by moving the actuation member relative to the elongatebody shaft, and dissecting the tissue region along the plane via the atleast one dissector arm member.

The tissue dissection assembly may include a number of optional featuresas well. For instance, although a single dissector arm member may beutilized in some variations, at least an additional dissector arm membermay be utilized and positioned along the actuation shaft and theelongate body shaft on an opposing side of the dissector arm member.Dissector arm members may extend in opposing directions along a singleplane into a dissecting configuration; alternatively, the arm membersmay be positioned such that they extend or reconfigure themselves alongdifferent planes relative to one another.

As the arm members deploy from their low profile shape, they may belocked into their expanded configuration or any intermediateconfiguration via a locking mechanism. Moreover, to facilitate insertionof the device through the tissue, a tapered or piercing distal tip,which may be optionally retractable, removable, or integrated as apermanent feature of the device, may also be included. When thedissector arm members are in their low profile configuration withrespect to the actuation shaft, the arm members may simply lie adjacentto the actuation shaft. Alternatively, the actuation shaft may defineopenings along a length of the actuation shaft adjacent to theirrespective arm members for receiving, at least partially within, theirrespective dissector arm members. In yet another alternative, theactuation shaft or elongate body shaft may be formed into a memberhaving a cross-sectional shape other than circular or tubular.

Actuation and locking of the arm members may be accomplished in a numberof different ways. For instance, a handle assembly coupled to a proximalend of the actuation and/or elongate body shaft may be configured toadvance and retract the arm members in a ratcheting manner to maintainone or more intermediate configurations of the arm members duringexpansion.

In another variation, the elongate body shaft may include a shaft distalportion which is configured to pivot at an angle relative to alongitudinal axis of the elongate shaft. The pivoting end effector maybe angled anywhere from 0 degrees to under 180 degrees to facilitateaccess and deployment within the patient body.

The dissector arm members themselves may be configured into variouscross-sectional geometries. Additionally, any of the dissector armmembers may be coated or covered with a compliant material to alter thefrictional properties of the dissector arm surfaces with respect to thetissue.

In yet another variation of the tissue dissector assembly, a pump may befluidly connected to the assembly to provide forinsufflation/exsufflation of a gas or fluid (e.g., air, carbon dioxide,saline, water, etc.) directly through the elongate body. This gas orfluid may be used before, during, or after mechanical dissection toalternatively initiate, enhance, or support dissection or to maintain orexpand a dissected space. Yet another variation may include a viewing orimaging port at a distal end of the assembly or alternatively along theelongate body or even through one or more of the dissector arm membersto provide for direct visualization during insertion into the tissue andduring dissection.

In another variation, a light source may be provided through theassembly directly. In yet another variation, an optional covering ormembrane may be disposed over the dissector arms to form a surface whichexpands and retracts along with the arms. Tissue retraction may beperformed without the covering or membrane at all and with the dissectorarms in any number of expanded configurations, i.e., fully or any numberof intermediate expanded configurations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B show perspective views of one variation of the tissuedissector and/or retractor in a low-profile configuration and anexpanded configuration, respectively.

FIGS. 2A and 2B show one example for percutaneously introducing thedevice of FIGS. 1A and 1B into a patient, e.g., to dissect layers oftissue within the abdominal wall.

FIGS. 2C to 2E show the device of FIGS. 2A and 2B expanded andsubsequently retracted within the patient body to dissect the tissueregion of interest.

FIG. 3A shows an example of one configuration for the dissector having atapered end for facilitating insertion into the patient body and betweentissue layers.

FIG. 3B shows another example of a configuration having a bluntedatraumatic tip and non-pivoting, expandable dissector arms.

FIG. 3C shows another example of a configuration having a bluntedatraumatic tip but with dissector arms which are pivotable relative tothe elongate shaft.

FIG. 3D shows another example having dissector arms which are configuredto be driven into an over-expanded configuration.

FIG. 3E shows yet another example of a single dissector arm expandableinto a looped configuration.

FIG. 3F shows another variation where each dissector arm member may bedirectly connected to a handle such that an actuation shaft may beomitted entirely.

FIG. 4A shows a detailed perspective view of a variation havingnon-pivoting expandable dissector arms.

FIGS. 4B and 4C show detailed perspective and top views of anothervariation having reconfigurable dissector arms slidable over a ring orcurved support member.

FIG. 4D shows another variation having a semi-circular support member.

FIG. 5A shows a partial cross-sectional top view of interleaveddissector arms held within the elongate support member such that thedissector arms are rotatable relative to one another over contactingbearing surfaces.

FIG. 5B shows a partial perspective view of one of the dissector armsillustrating the bearing surface.

FIGS. 5C and 5D show top and side views, respectively, of anothervariation in which the distal ends of the dissector arm members may bekeyed to traverse through respective slots or grooves defined within ahousing member.

FIG. 5E shows an exploded assembly view of the housing member of FIGS.5C and 5D.

FIGS. 6A to 6C show cross-sectional end views of the dissector armassembly in low-profile configurations illustrating various assemblyconfigurations where the dissector arms may be profiled adjacent to theactuation shaft, partially within the actuation shaft, or having theelongate body shaft in a non-circular shape.

FIGS. 6D to 6F show end views of alternative variations where two ormore dissector arms may be angled relative to one another.

FIG. 7 illustrates a cross-sectional side view of one example for ahandle assembly optionally configured to ratchet the dissector arms intoany number of deployed and retracted configurations.

FIG. 8A shows a side view of an expanded and various intermediateconfigurations where both dissector arms may be simultaneously actuated.

FIGS. 8B and 8C show side views of alternative expanded and variousintermediate configurations where either dissector arm may be actuatedsingularly.

FIG. 9A shows an example of another variation where the tissue dissectorend effector may be optionally pivoted via a passive or active mechanismrelative to the elongate body shaft to facilitate access and use withinthe patient body.

FIG. 9B shows a partial cross-sectional view of one example for pivotingthe end effector assembly relative to the elongate body shaft.

FIG. 10 illustrates an exemplary tissue dissector assembly.

FIGS. 11A to 11K illustrate some examples for various cross-sectionalprofiles for the dissector arm members.

FIG. 12 shows another variation of the tissue dissector assembly havingan integrated pumping mechanism to provide for insufflation and/or fluidinjection through the assembly.

FIG. 13 shows yet another variation having an integrated video imagingassembly to provide visualization during insertion, dissection, orretraction into or from the patient body.

FIGS. 14A and 14B show detailed views of yet another variation where avideo imaging system may be advanced through the tissue dissectorassembly to provide direct visualization of the tissue region beingdissected or retracted.

FIG. 15 shows yet another variation of the tissue dissector assemblywhere the dissector arms themselves may be configured to directly emitlight to provide lighting during visualization.

FIG. 16 shows yet another variation of the tissue dissector assemblyhaving an optional distensible covering over the dissector arms forcreating a surface for tissue retraction.

FIG. 17 shows the variation of the assembly of FIG. 16 being utilized toretract an organ within the patient body.

DETAILED DESCRIPTION OF THE INVENTION

Dissection of tissue and tissue layers may be accomplishedpercutaneously through one or more incisions made in a patient's skin orthrough an open surgical procedure. An instrument which enables asurgeon to obtain access within a patient's body through controlleddissection between tissue layers within a plane or along a line is shownin the perspective view of FIG. 1A, which shows one example of a tissuedissector assembly 10 in a low profile configuration for insertion intothe tissue region of interest. FIG. 1B shows tissue dissector assembly10 in a fully expanded tissue dissection configuration.

Such a variation of tissue dissector assembly 10 may generally comprisean elongate body shaft 12 appropriately sized, e.g., similarly to aconventional surgical or laparoscopic instrument, having a tissuedissector end effector 14 located at a distal end of elongate body shaft12. Handle 16 may be coupled proximally of body shaft 12 formanipulating an actuation shaft 18 and an atraumatic tip 20 may beattached at a distal end of assembly 10 to facilitate its insertion intothe tissue region to be dissected within the patient. Actuation shaft 18may comprise an elongate member configured to be slidably positionedthrough a lumen of body shaft 12.

At least a first end of a single dissector arm member 22 may be attachedat arm member attachment 26 to a distal end of actuation shaft 18 and asecond end may be attached to a distal end of elongate body shaft 12.Although actuation shaft 18 is shown in the figures as extendingentirely through body shaft 12 through body shaft lumen 30, actuationshaft 18 may extend at least partially through, over, or alongside bodyshaft 12 in other variations of the assembly 10. Moreover, in othervariations, a secondary shaft may be coupled to a proximal end ofactuation shaft 18 such that the secondary shaft extends proximally tohandle 16.

Although a single dissector arm member 22 may be utilized in somevariations, at least an additional dissector arm member 24 may beutilized and positioned as shown along actuation shaft 18 and elongatebody shaft 12 on an opposing side of dissector arm member 22. Dissectorarm members 22, 24 may be positioned along assembly 10, e.g., at 180degrees with respect to one another, so that when they are actuated todeploy, arm members 22, 24 may extend in opposing directions along asingle plane into a dissecting configuration, as shown in FIG. 1B.Alternatively, arm members 22, 24 may be positioned such that theyextend or reconfigure themselves along different planes, as furtherdescribed below.

Each of the arm members 22, 24 may be fabricated from a biocompatiblematerial such as flexible or compliant metal, e.g., spring stainlesssteel or a superelastic or shape memory alloy such as Nitinol, so thatonce arm members 22, 24 have been reconfigured from their low profileshape to their expanded shape, the arms may collapse back into their lowprofile. Alternatively, arm members 22, 24 may be fabricated frominflexible or partially flexible metals or polymers which are connectedvia one or more hinges, e.g., pivoted hinges or living hinges, etc.,along the length of arm members 22, 24 to enable reconfiguration of armmembers 22, 24. In yet another alternative, arm members 22, 24 may befabricated from any number of flexible polymeric materials, e.g.,polycarbonate, polyethylene, polyamide, etc. Moreover, these flexiblepolymeric arm members 22, 24 may be optionally fabricated to betranslucent such that tissue being dissected and/or retracted may bevisualized directly through the translucent arm members 22, 24 fromwithin the patient body utilizing any number of imagers, as furtherdescribed below.

As arm members 22, 24 deploy from their low profile shape, as shown inFIG. 1A, they may locked into their expanded configuration, as shown inFIG. 1B, or any intermediate configuration via locking mechanism 28,which may be located along elongate body shaft 12, actuation shaft 18,or handle 16. To release the locked configuration of arm members 22, 24,locking mechanism 28 may be re-depressed. Locking mechanism 28 is shownas a push-button mechanism, however, any number of conventional lockingmechanisms for maintaining the relative position of actuation shaft 18with respect to elongate body shaft 12 may be utilized, e.g., frictionlocks, ratcheting mechanisms (as shown below), pin locks, etc.

In use, one method may generally comprise inserting the assembly 10 intoa patient body 40 through an incision 42, e.g., through a patient'sumbilicus and into the abdominal wall as shown in FIG. 2A, with armmembers 22, 24 in their low profile configuration. The atraumatic tip 20of the device may prevent unnecessary trauma to the surrounding tissueas the device is inserted blindly, under direct vision, or through aseparate videoscope. In other variations, a videoscope or imager may beintegrated or included within the device, as described below in furtherdetail. In either case, the device may be pushed, e.g., towards thepubic bone, while maintaining a presence within a desired tissue plane.Once the tissue plane is to be dissected, handle 16 may be advanced withrespect to elongate body shaft 12 such that arm member 22, 24 areexpanded to thereby dissect the surrounding tissue along the desiredtissue plane, as shown in FIG. 2B.

FIGS. 2C to 2E show end views of an example of the tissue dissectionassembly 10 during a tissue dissection procedure. As previouslydescribed, the device may be inserted into the tissue region of interestTI between adjacent tissue planes with arm member 22, 24 in their lowprofile shape, as shown in FIG. 2C. Arm member 22, 24 may then beexpanded, either fully or to an intermediate position, to therebydissect the surrounding tissue TI from one another, as shown in FIG. 2D.Expansion of arm member 22, 24 may be continued or retracted to therebyleave an open region D between adjacent tissue layers, as shown in FIG.2E.

The arm member 22, 24 may also be deployed and retracted as many timesas necessary until the desired degree of tissue separation or dissectionhas occurred.

Additionally, the device may be applied in a sweeping motion, e.g.,left-to-right, or rotated about its longitudinal axis by any number ofdegrees until the tissue planes have been appropriately separated.Moreover, insufflation of a gas or fluid may optionally be utilizedthrough a separate instrument or through the assembly itself to furtheraid tissue dissection, as described below in further detail.

Aside from use for dissection of tissue surrounding the peritonealspace, the assembly may be utilized in a number of different regionsthroughout the body. For example, the device may be inserted into thebody for providing access to the kidneys in the extra-peritoneal space,to the prostate in the pre-peritoneal space, or for providing vascularaccess. The assembly may also be utilized for providing access toregions in the legs, arms, etc., as so desired.

To facilitate insertion of the device through the tissue, a tapered orpiercing distal tip 50 may be included, as shown in FIG. 3A. Thispiercing distal tip 50 may be optionally retractable, removable, orintegrated as a permanent feature of the device. The dissector armmembers may be configured to expand from a low profile into an expandedprofile having any number of expanded configurations. For instance, asmentioned above, the distal ends of dissector arms 22, 24 may beattached to the distal end or portion of actuation shaft 18 via asecurement member 52, e.g., band, ring, etc., as shown in FIG. 3B, orthe arms 22, 24 may be simply attached directly into receiving channelsor via an adhesive in other variations. Allowing for such a non-pivotingattachment may allow for arm members 22, 24 to conform into asymmetrically arcuate or curved configuration. Alternatively, thedissector arms may be pivotably connected via a pivot or pinnedconnection 58 which may allow for arm members 54, 56 to conform into anasymmetric curve, as shown in FIG. 3C.

In yet another alternative, arm members 60, 62 may be connected viapivot or pinned connection 64 while actuation shaft 18 is overdrivenwith respect to elongate body shaft 12. Overdriving actuation shaft 18may conform arm members 60, 62 into an overextended arcuateconfiguration, as shown in FIG. 3D. In another variation, a singledissector arm 66 may be utilized to form a single looped configuration,as shown in FIG. 3E. A first end of looped arm 66 may be connected at afixed attachment point 70 and a second end of looped arm 66 may beconnected at a fixed attachment point 72 to an actuation shaft which istranslatably disposed with respect to elongate body shaft 12.Translation of the actuation shaft relative to elongate body shaft 12may deploy looped arm 66 from its low profile configuration into itsfully deployed configuration, or into any number of intermediatepositions or configurations by moving a single side of dissector arm 66in the direction of the arrow shown in FIG. 3E.

Turning to FIG. 3F, an example of an instrument similar to that shown inFIG. 3E is shown. A single looped dissector arm may be employed, but inthis variation, two separate dissector arms 74, 76 are illustratedrotatingly joined via rotating attachment 73. Each of the dissector arms74, 76 may extend entirely through shaft 12 and attach directly to ahandle 78, which may be urged distally and proximally in the directionsshown to expand or retract dissector arms 74, 76, as shown by theirrespective arrows. In this variation, because the proximal ends ofdissector arms 74, 76 are attached directly to the handle, an actuationshaft may be omitted entirely. Other features, e.g., locking mechanismsor ratcheting mechanisms described herein, may be integrated incombination with this embodiment, as so desired.

In alternative variations, each of the dissector arm members mayattached in alternating methods. For instance, in the example of FIG.4A, a first dissector arm 22 may be connected via a pivoting attachment80 while the second arm dissector arm 24 may be attached to securementmember 52 via a non-pivoting attachment such that each arm 22, 24conforms to a different configuration. In yet another alternative shownin FIG. 4B, each of the distal ends of the dissector arm members 22, 24may comprise a looped connector 84 which slides along a loopedattachment member 82 positioned at the distal end of actuation shaft 18.When actuation shaft 18 is thus actuated, each of the dissector armmembers 22, 24 may slidingly rotate about looped attachment member 82 ina non-pivoting manner to expand the arm members 22, 24.

FIG. 4C shows a detailed side view of the looped attachment of FIG. 4B.As illustrated, looped attachment member 82 may be formed as a circularring attached to a distal end of actuation shaft 18. Looped connectors84 at the distal ends of dissector arm members 22, 24 may slide alonglooped attachment member 82. Although the looped attachment member 82 isshown in this variation as a circular member, other configurations maybe utilized, as practicable. For instance, FIG. 4D shows a semi-circularattachment member 88 over which angled connectors 86 located at thedistal ends of dissector arm members 22, 24 may slide over or upon.Other shapes for attachment members may also include elliptical, angled,straight, triangular, etc.

Another variation for arm member connection is shown in the detailpartial cross-sectional top view in FIG. 5A of actuation shaft 18 androtational connection 90 of the interleaved distal ends of arm members22, 24. As illustrated in the partial perspective view of FIG. 5B, thedistal ends of arm members 22, 24 may be formed into an interleavedelement or member 92 which together form a complementary and rotationalconnection, as shown in FIG. 5A. When the two arm members 22, 24 areinterleaved with one another, they may be securely held within actuationshaft 18 while also allowing for free rotation with respect to oneanother without the need for a pivot joint or connection.

Yet another variation for arm member connection is shown in FIGS. 5C to5E, which shows a keyed connection for the arm members. As seen in FIG.5C, a keyed attachment housing 94 may be disposed at a distal end ofactuation shaft 18 and have distal ends of dissector arm members 22, 24slidingly connected within housing 94. FIG. 5D shows a side view ofattachment housing 94, which, in one variation, may be comprised ofindividual corresponding half members 94A, 94B which may be connected toone another and/or to actuation shaft 18 in a correspondingcomplementary attachment. Members 94A, 94B connected to actuation shaft18 may define a slot 96 between the corresponding members 94A, 94Bthrough which the dissector arm members 22, 24 may traverse whenexpanding or retracting.

FIG. 5E shows an exploded assembly view of the attachment housingmembers 94A, 94B and the keyed distal ends 93A, 93B of their respectivedissector arm members 22, 24. Keyed channels, slots, or grooves 98A, 98Bmay be defined within attachment housing member 94A while correspondingchannels, slots, or grooves 99A, 99B may be likewise defined withinattachment housing member 94B. When attachment housing members 94A, 94Bare correspondingly positioned relative to one another, each of theslots 98A, 98B may face in apposition to their respective slots 99A, 99Bsuch that the distal end of dissector arm member 22 having a bearing orsliding member 93A may be keyed to traverse within the apposed slots 98Aand 99A. Likewise, the distal end of dissector arm member 24, alsohaving a corresponding bearing or sliding member 93B, may be keyed totraverse within the apposed slots 98B and 99B.

Each of the apposed slots 98A, 99A and 98B, 99B may be defined in acurved or arcuate path within their respective attachment housingmembers 94A, 94B such that when dissector arm members 22, 24 areexpanded or retracted during a procedure, their bearing or slidingmembers 93A, 93B may freely slide securely within their respectiveslots.

When the dissector arm members 22, 24 are in their low profileconfiguration with respect to the actuation shaft 18, the arm members22, 24 may simply lie adjacent to actuation shaft 18, as shown in thepartial cross-sectional end view of FIG. 6A. The arm members 22, 24,when in their low profile configuration, may have a diameter which isless than or equivalent to a diameter of elongate body shaft 12.Dissector arm members 22, 24 are shown in this example as each having arespective dissecting edge 110, 112 defined along an outer surface ofeach arm members 22, 24 to facilitate the dissection of tissue.

In another variation, actuation shaft 100 may define openings 102, 104along a length of actuation shaft 100 adjacent to their respective armmembers 106, 108 for receiving, at least partially within, theirrespective dissector arm members 106, 108, as shown in thecross-sectional end view of FIG. 6B. Arm members 106, 108 may rest atleast partially within their openings 102, 104 when in their low profilefor advancement into a patient body. Upon deployment to their expandedprofile, arm members 106, 108 may deploy as described above.

In yet another alternative, actuation shaft 18 or elongate body shaft114 may be formed into a member having a cross-sectional shape otherthan circular or tubular. For example, as shown in the example of FIG.6C, elongate body shaft 114 may be formed to have an elliptical or ovalcross-section. Other cross-sectional shapes may be utilized as desiredand as practicable, e.g., triagonal, square, octagonal, etc.

In other variations, the arm members may be angled with respect to oneanother such that they expand in a non-planar manner. The example shownin FIG. 6D illustrates arm members 22A, 22B each at some angle, Θ, whichmay be greater than 0 degrees and less than 90 degrees with respect toactuation shaft 18. In yet other variations, more than one or two armmembers may be utilized, as shown in the example of FIG. 6E, whichillustrates in end view four arm members 22A, 22B, 22C, 22D which mayuniformly spaced about actuation shaft 18 with respect to one another.FIG. 6F shows another example utilizing three arm members 22A, 22B, 22Cwhich may be uniformly spaced from one another about actuation shaft 18.These examples are not intended to be limiting in any way and arepresented merely as examples. Other variations in number of arm membersand spacing and angling between arm members are intended to be includedin this disclosure.

Actuation and locking of the arm members may be accomplished in a numberof different ways. FIG. 7 shows one example of an alternative handleassembly 120 which may be utilized. Such a handle assembly 120 may beconfigured to advance and retract the arm members in a ratcheting manneras well as to maintain one or more intermediate configurations of thearm members during expansion. Handle assembly 120 may be coupled to aproximal end of elongate body shaft 12 and actuation shaft 18 andmanipulated externally of a patient body.

Generally, handle assembly 120 may comprise housing 122 to which one ormore handle members 124, 128 may be attached. Each handle member mayhave a respective actuation or retraction handle aligned in appositionfor either advancing or retracting the actuation shaft 18 relative toelongate body shaft 12. For example, handle member 124 may haveactuation handle 126 for actuating the advancement of actuation shaft 18relative to elongate body shaft 12 to expand the arm members and handlemember 128 may have retraction handle 130 in apposition therewith foractuating the retraction of actuation shaft 18 relative to elongate bodyshaft 12 to retract the arm members. Each of the actuation handles 126,130 may pivot about respective pivots 132, 148 and may also include abiasing element, such as respective spring members 134, 150 formaintaining a bias in each actuation handle 126, 130. Each of theactuation handles 126, 130 may be further pivotably connected at pivots138, 154 within housing 122 to a respective pawl member 136, 152.

Each of the pawl members 136, 152 may be biased to rest against abi-directional rack member 140 having a first set of angled teeth orprojections 142 on a first side of rack member 140 and a second set ofangled teeth or projections 144 on a second side of rack member 140where the second set of projections 144 are angled in an oppositedirection to the first set of projections 142. The first set 142 may beangled in a first direction with respect to pawl 136 to advance rack 140in a first distal direction 146 when engaged by pawl 136 to expand thearm members. Manipulation of actuation handle 126 relative to handle 124may thus move pawl member 136 in a reciprocating manner to engage firstset 142 and advance rack 140 distally with each stroke. Likewise,manipulation of actuation handle 130 relative to handle 128 may likewisemove pawl member 152 in a reciprocating manner to engage second set 144and advance rack 140 in a proximal direction 156 with each stroke. Aproximal end of actuation shaft 18 may be coupled to rack 140 viaconnection 158. Alternatively, a proximal portion of actuation shaft 18may be formed into a bi-directional rack.

This optional ratcheting of the arm member expansion and retraction mayenable a controlled deployment of the arm members. Moreover, lockingmechanisms may be incorporated in handle assembly 120 to ensure thatonce the arm members have been expanded to their fully deployedconfiguration or to any intermediate configuration, a configuration ofthe arm members may be set and maintained despite releasing the handles.An example for incorporating locking features may also be seen in FIG. 7in locking member 160 having a rack engagement 162 and locking member166 having a rack engagement 168. Locking members 160, 166 may each havea respective biasing element such as spring elements 164, 170 forengaging and locking rack member 140 during advancement and retractionto ensure that release of handles 126, 130 does not release rack member140.

As mentioned above, dissector arm members 22, 24 may be deployed,expanded, or retracted in any number of intermediate configurations 180.Moreover, expansion and retraction of arm members 22, 24 may beaccomplished simultaneously such that the arm members 22, 24 dissect thesurrounding tissue on either side in a simultaneous manner, as shown inFIG. 8A. Alternatively, either arm member may be actuated and deployedindependently from one another. FIG. 8B shows one example where armmember 22 may be expanded and retracted either fully or in any number ofintermediate positions 182 while maintaining the other arm member 24 inits low profile position. Likewise, FIG. 8C shows another example wherethe other arm member 24 may be expanded and retracted also either fullyor in any number of intermediate positions 184 while maintaining the armmember 22 in its low profile position.

Another feature which may be optionally incorporated into the assemblymay include a pivoting tissue dissector end effector 190, as shown inthe perspective view of FIG. 9A. In such a variation, elongate bodyshaft 192 may include a shaft distal portion 194 which is configured topivot at an angle, α, relative to a longitudinal axis of elongate shaft192. Pivoting end effector 190 may be angled anywhere from 0 degrees tounder 180 degrees to facilitate access and deployment within the patientbody. Even when angled, dissector arm members 196, 198 may be expandedand retracted in any number of configurations, as described above.

In pivoting end effector 190, various active or passive mechanisms maybe employed. For instance, pivoting end effector 190 may be configuredto self-pivot to a set pre-determined angle, a, e.g., 45 degrees. Insuch an embodiment, a bending or pivoting portion proximal to endeffector 190 may be fabricated from a spring stainless steel or shapememory alloy such as Nitinol such that when the instrument is deployed,unlocked, or otherwise unconstrained, end effector 190 automaticallyreconfigures to curve, angle, or curl into its predetermined deploymentconfiguration, such as that shown in FIG. 9A.

FIG. 9B shows a detail partial cross-sectional view of the distalportion of elongate body shaft 192 and shaft distal portion 194 toillustrate another example for a pivoting mechanism 200. This exampleshows an actively actuated pivoting, bending, or curling mechanism. Asshown, an actuation shaft 204 for actuating dissector arm members 196,198 may extend through lumen 218 defined through shaft 192 and 194. Aportion of actuation shaft 204 may include a bending or pivoting portion202 which may transmit a longitudinal actuation force along the curvedor angled portion 202. The pivoting portion 202 may be comprised of areduced section of actuation shaft 204 capable of bending repeatedly orit may alternatively be comprised of a linkage to enable forcetransmission over a curved or angled section.

Shaft distal portion 194 may be pivotably attached to elongate bodyshaft 192 via dissector assembly pivot 206 to enable free rotation ofshaft distal portion 194 relative to elongate body shaft 192 whenactuated via pivot actuation shaft 208. The proximal end of pivotactuation shaft 208 may be routed through and/or connected to the handleassembly to allow for manipulation of shaft 208. By urging shaft 208distally or proximally, a longitudinal force may be transmitted toactuate shaft distal portion 194, which may in turn transmit this forceto pivot shaft distal portion 194 relative to elongate body shaft 192,e.g., to some angled position as illustrated by an example of displacedposition 216. The angle by which distal portion 194 may pivot relativeto body shaft 192 may be determined by a number of different methods,e.g., the angle, β, over which pivot 214 traverses with respect to pivot206 when actuation shaft 208 is urged distally or proximally. Shaft 208may be coupled to distal portion 194 via pivot linkage 210, which may inturn be pivotably coupled to distal portion 194 via pivot 214 and toactuation shaft 208 via pivot 212. The details for pivoting distalportion 194 are intended to be merely illustrative and are not intendedto be limiting in any way.

Turning now to variations in dissector arm members, FIG. 10 shows anexample of tissue dissector assembly 10 and dissector arm members 22,24. FIGS. 11A to 11K show examples of some of the various cross-sectionsinto which dissector arm members 22, 24 may be formed. These examplesare intended to be illustrative of various configurations and are notintended to be limiting in any way. Other configurations for dissectingtissue which are not shown but which are obvious are intended to beincluded.

FIG. 11A shows a square cross-section 220 which may be potentiallyutilized although such a blunt cross-section may not be optimized fordissecting tissue. FIG. 11B shows an example in partially curvedcross-section 222 having a curved outer surface 224 for contacting anddissecting the tissue. FIG. 11C shows another example in curvedcross-section 226 which has a curved outer surface 224 and a concavelycurved inner surface 228. FIG. 11D shows a tapered cross-section 230having a partially blunted outer surface while FIG. 11E shows a taperedcross-section 232 having a cutting tip 234 for dissecting tissue. FIG.11F shows a similarly tapered cross-section 236 having a diamond-shape.FIG. 11G shows a tissue cutting cross-section 238 having a partiallyrectangular portion which tapers into a cutting tip 234. FIG. 11H showsanother cross-section in a tear-shaped configuration 240. FIG. 11I showsa circular cross-section 242 and FIG. 11J shows another cross-section244 which is elliptically shaped. Finally, FIG. 11K shows across-section which is comprised generally of a curved outer surface anda convex inner surface configuration 246.

In addition to various cross-sectional geometries, any of the dissectorarm members may be additionally coated or covered with a compliantmaterial to alter the frictional properties of the dissector armsurfaces. For instance, they may be covered with a material, e.g.,polymers, to further decrease any frictional resistance against tissue.Alternatively, the dissector arm surfaces may be coated or covered witha material, e.g., mesh, silicone, etc., to further increase thefrictional resistance against the tissue. Alternatively, the dissectorarm surfaces may be roughened or patterned with projections tomechanically increase tissue resistance. In yet another variation, thearms may be coated with drug such as antibiotics, anti-thrombin agents,etc., to facilitate tissue healing after dissection.

In yet another variation of the tissue dissector assembly 10, FIG. 12shows an example in which a pump 254 may be fluidly connected toassembly 10 via fluid line 252 to provide for insufflation/exsufflationof a gas or fluid 256 (e.g., air, carbon dioxide, saline, water, etc.)directly through elongate body 12. This gas or fluid may be used before,during, or after mechanical dissection to alternatively initiate,enhance, or support dissection or to maintain or expand a dissectedspace. One or more fluid channels may be routed through elongate body 12to a respective port or opening 250 located along assembly 10 or at itsdistal end. In another variation, one fluid channel may be dedicated asan insufflation port to enable insufflation during tissue dissectionwhile a second fluid channel may be dedicated as a fluid delivery port.

In another variation, FIG. 13 shows a perspective view of a tissuedissector assembly 10 having an additional viewing or imaging port 260located at a distal end of assembly 10. The imaging port 260 may bealternatively located along elongate body 12 or even through one or moreof dissector arm members 22, 24 to provide for visualization duringinsertion into the tissue, during dissection, and/or during retractioninto or from the patient body. A cable 262 may be coupled to assembly 10and routed to a video processor 264 for processing any images fordisplay. Any number of conventional imaging modalities may be utilizedas desired, e.g., CCD chips, fiber optic imaging fibers, etc., which maybe inserted through elongate body 12 as a separate instrument orintegrated directly with assembly 10.

FIGS. 14A and 14B show detail perspective views of another alternativefor providing visualization within the patient body during a procedure.In this variation, actuation shaft 270 may also serve as a viewing shaftby having one or more openings or slots 272 defined along its outersurface, as shown in FIG. 14A. These slots 272 may be defined on one orboth sides of actuation shaft 270 adjacent to dissector arms 22, 24.During a procedure, a visualization instrument such as scope 274 havingan imager 276 and a light source may be advanced through elongate body12 and actuation shaft 270, as shown in FIG. 14A. Before, during, orafter dissector arms 22, 24 are deployed into their expandedconfiguration, imager 274 may be pointed through either opening 272 toprovide for visualization of the tissue being dissected or of the tissueregion in general, as shown in FIG. 14B. As mentioned above, dissectorarm members 22, 24 may be optionally configured to be translucent inwhich case the dissected tissue and/or surrounding tissue may bevisualized directly through the translucent arm members 22, 24 fromwithin the patient body utilizing imager 276.

In yet another variation, a light source may be provided through theassembly directly. Optical fibers may route the light emitted from anexternal light source 286 via light transmission cable 284 directlythrough elongate body 12 to aid visualization of the tissue region. Anadditional visualization instrument may be integrated or deliveredthrough the assembly, as described above, while coupled via cable 288 toa video processor 290. Alternatively, an integrated light source 292 maybe positioned along the assembly. Examples of integrated light sourcesmay include, e.g., light emitting diodes. In yet another variation,dissector arm members 280, 282 may be fabricated from a lighttransmitting material, such as polycarbonate, which may transmit lightdirectly from light source 286 to the surrounding tissue, as shown inFIG. 15. In such an embodiment, light transmitting arm members 280, 282may not only provide a direct light source to the dissected andsurrounding tissue, but the tissue may also be visualized directlythrough the translucent arm members 280, 282, as described above forFIG. 14B. Alternatively, light transmitting optical fibers may be routeddirectly through dissector arms 280, 282 to provide for light to thetissue.

In another variation of the tissue dissector assembly, an optionalcovering or membrane 300, e.g., polyurethane, silicone, etc., may bedisposed over dissector arms 22, 24 to form a surface which expands andretracts along with the arms, as shown in FIG. 16. Covering or membrane300 may be utilized to facilitate use of the tissue dissector assemblyfor tissue or organ retraction along with the tissue dissectioncapabilities of the assembly. An example of the assembly for organretraction is shown in FIG. 17, which shows the assembly retracting anorgan 302, liver, bowel, fat, kidneys, etc., within the patient body.Tissue retraction may be performed without the covering or membrane 300at all and with dissector arms 22, 24 in any number of expandedconfigurations, i.e., fully or any number of intermediate expandedconfigurations.

The applications of the apparatus and methods discussed above are notlimited to the disclosed features. Modification of the above-describedassemblies and methods for carrying out the invention, and variations ofaspects of the invention that are obvious to those of skill in the artare intended to be within the scope of the claims. Furthermore, variousfeatures of the dissector arms, visualization, lighting, etc., may becombined with one another in any number of combinations as practicableand are intended to be within the scope of this disclosure.

1. A tissue dissection assembly, comprising: an elongate rigid or whollyflexible body shaft which is sized for introduction between layers ofbody tissue; an actuation member movable relative to the elongate bodyshaft; and a first dissector arm member and a second dissector armmember each having at least a first end attached to a distal tip of theelongate body shaft and where each arm member has a substantiallyuniform cross-section along its length, wherein each dissector armmember is comprised of a translucent material to facilitatevisualization of the body tissue and is positioned along the elongatebody shaft opposite to one another such that each arm memberreconfigures radially to be set and maintained in one or moreintermediate positions via an intermediate stop mechanism whereby eacharm member is correspondingly configured within a single plane from alow profile to an expanded curved or arcuate planar profile along asubstantial length of each arm member when urged via the actuationmember such that the assembly dissects the body tissue along the singleplane, and wherein each dissector arm member is further positioned alongthe elongate body shaft such that each dissector arm member isreconfigurable into an overextended arcuate configuration extendingdistally beyond the assembly.
 2. The assembly of claim 1 furthercomprising a handle assembly coupled to a proximal end of the elongatebody shaft for actuating a reconfiguration of each dissector arm member.3. The assembly of claim 2 wherein the handle assembly is adapted toactuate each dissector arm member in a plurality of intermediateconfigurations between the low profile and the expanded profile.
 4. Theassembly of claim 1 wherein the assembly further comprises a pivot forconfiguring each dissector arm member at an angle relative to alongitudinal axis of the elongate body shaft proximal to each dissectorarm.
 5. The assembly of claim 1 further comprising a pump in fluidcommunication with the elongate body shaft.
 6. The assembly of claim 1further comprising an imaging assembly disposable through the elongatebody shaft for providing visualization therethrough.
 7. The assembly ofclaim 6 wherein the imaging assembly comprises a videoscope or imagingchip disposed within or through the elongate body shaft.
 8. The assemblyof claim 1 further comprising a lighting source optically coupled to theassembly.
 9. The assembly of claim 1 wherein each dissector arm isadapted to simultaneously reconfigure within the plane from the lowprofile to the expanded profile.
 10. The assembly of claim 1 whereineach dissector arm is adapted to reconfigure within the plane from thelow profile to the expanded profile independently of one another. 11.The assembly of claim 1 further comprising a tip tapered to facilitatepiercing into or along tissue.
 12. The assembly of claim 1 wherein asecond end of each dissector arm is attached to the actuation membersuch that advancement of the actuation member relative to the elongatebody shaft urges the first and second dissector arm members toreconfigure.
 13. The assembly of claim 12 wherein the actuation memberdefines at least one channel or opening adapted to receive eachdissector arm in its low profile configuration.
 14. The assembly ofclaim 1 wherein each dissector arm defines a tapered or arcuate outersurface for facilitating tissue dissection.
 15. The assembly of claim 1wherein each dissector arm is comprised of a superelastic alloy.
 16. Theassembly of claim 1 further comprising a distensible membrane orcovering for expansion with each dissector arm member.
 17. The assemblyof claim 1 wherein all the arm members lie within the single plane. 18.The assembly of claim 1 wherein each first end of each arm member ispivotably attached to the elongate body shaft such that each first endis overlaid movably atop one another.
 19. The assembly of claim 1further comprising a pivoted mechanism positioned along the elongatebody shaft rotatably coupling a distal section and a proximal sectionand having the actuation member extending therethrough, wherein thedistal section having the arm members is pivoted at an angle relative tothe proximal section of the elongate body shaft when the actuationmember is actuated longitudinally.
 20. The assembly of claim 19 whereinthe actuation member has a bending section comprised of a reduceddiameter capable of bending when translated within the pivotingmechanism.
 21. A method of dissecting tissue within a plane, comprising:advancing a tissue dissection assembly having an elongate rigid bodyshaft which is at least partially rigid and sized for introductionbetween layers of adjacent tissue planes of body tissue into a tissueregion to be dissected; urging a first dissector arm member and a seconddissector arm member positioned along the elongate body shaft oppositeto one another to reconfigure radially within a single plane from a lowprofile to an expanded curved or arcuate profile by moving an actuationmember relative to the elongate body shaft, wherein each dissector armmember is comprised of a translucent material to facilitatevisualization of the body tissue; and dissecting the tissue region alongthe single plane such that each dissector arm member expands within andbetween the single plane and separates the adjacent tissue planes fromone another by being positioned planarly within the tissue region suchthat each dissector arm member is reconfigurable into an overextendedarcuate configuration extending distally beyond the assembly.
 22. Themethod of claim 21 wherein advancing comprises advancing the elongatebody shaft percutaneously into the tissue region.
 23. The method ofclaim 21 wherein urging comprises advancing the actuation member throughor along the elongate body shaft such that each dissector arm memberreconfigures.
 24. The method of claim 21 wherein urging comprises urgingeach dissector arm member simultaneously.
 25. The method of claim 21wherein urging comprises urging each dissector arm member independentlyof one another.
 26. The method of claim 21 wherein urging comprisesurging each dissector arm into at least one intermediate configurationbetween the low profile configuration and the expanded profileconfiguration.
 27. The method of claim 21 further comprising retractingeach dissector arm from the expanded profile into an intermediateprofile.
 28. The method of claim 21 further comprising imaging thetissue region prior to or while dissecting.
 29. The method of claim 21further comprising insufflating the tissue region prior to or whiledissecting.
 30. The method of claim 21 further comprising retracting thetissue region via each dissector arm member.
 31. The method of claim 21further comprising pivoting a distal section of the elongate body shaftrelative to a proximal section via a pivoted mechanism which rotatablycouples the distal section and the proximal section and has an actuationmember extending therethrough such that the arm members are pivotedrelative to the proximal section when the actuation member is actuatedlongitudinally.
 32. The method of claim 31 wherein pivoting comprisestranslating the actuation member through the elongate body shaft until abending section comprised of a reduced diameter is translated within thepivoting mechanism along the elongate body shaft.